Warp knit fabric and method and apparatus for making the same



N. K. SHARPE WARP KNIT FABRIC AND METHOD AND APPARATUS FOR MAKING THE SAME Filed Dec 13, 1967 Nov. 17, 1970 5 Sheets-Sheet 2 INVENT OR ATTOR NEYS N. K. SHARPE Nov. 17, 1970 WARP KNIT FABRIC AND METHOD AND APPARATUS FOR MAKING THE SAME 5 Sheets-Sheet 5 Filed Dec. 13, 1967 INVENTOR JVZ J if JZ fiE/ A fidwk ATTORNEYS N. K. SHARPE Nov. 17, 1970 WARP KNIT FABRIC AND METHOD AND APPARATUS FOR MAKING THE SAME Filed Dec. 13, 1967 5 Sheets-Sheet 4.

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444 ATTORNEYS Nov. 17, 1970 N. K. SHARPE 3,540,238

WARP KNIT FABRIC AND METHOD AND APPARATUS FOR MAKING THE SAME Filed Dec. 13, 1967 5 Sheets-Sheet 5 JV/F5 K1577495 5 IN VENTOR ATTORNEYS States 3,540,238 WARP KNIT FABRIC AND METHOD AND APPARATUS FQR MAKING THE SAME Ned K. Sharpe, Burlington, N.C., assignor to Burlington Industries, Inc., Greensboro, N.C., a corporation of Delaware Filed Dec. 13, 1967, Ser. No. 690,347 Int. Cl. D04b 23/10 US. Cl. 66-192 3 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a fabric and apparatus and method for making a fabric. More specifically, it pertains to a kind of fabric having loose fibers, filling yarn or other filling materials through and along which have been formed chain stitches produced by warp knitting. The invention is particularly concerned with a yarn laid against the fabric and held down against it by the aforesaid stitches, and to ornamental or other patterns produced by that yarn.

For p.1rposes of simplicity, the term sewing will be used herein to refer to the warp knitting operation. This term has found use in the textile industry in connection with this kind of fabric and avoids confusion because the word warp is used to refer to another yarn employed in this type of fabric, as will be explained below. Similarly, for convenience, the threads which form these loops are referred to as sewing thread.

Fabrics of this type can be made by forming a plurality of chain stitched rows of loops of sewing thread along a variety of filling materials, including an array of loose fibers, e.g. a batting, loose filling yarn, woven fabrics and other sheet-like materials. For present purposes, this material will be referred to as the filling. The stitches pass through the material at spaced points along the machine direction of the fabric and gather loose filling yarn, and to a certain extent loose fibers in a batting, into a plurality of clusters separated by spaces corresponding to the stitch insertion points. A plurality of stitches are formed simultaneously across the material, so that the spaces tend to be essentially continuous across the fabric, especially where yarns are used as the filling.

In a particularly important form of these fabrics the stitches of adjacent loop chains are interlocked, that is the warp knitting uses a tricot stitch. This effect may be obtained by the manner in which the sewing thread is supplied to loop forming needles. The thread passes through guides which oscillate between adjacent needles, so that each sewing thread end is alternately supplied to adjacent sewing needles, and each chain contains loops alternately formed from two different threads. This type of stitch has several advantages. First, the interknitting of the two sewing ends increases the durability of the fabric. If simple chain stitching is used, one break in a sewing thread may result in an entire chain of loops being pulled out. In the interlocking stitch described above, each sewing thread is interlocked with two others; therefore, a broken thread will be held by two others.

atent Another advantage of this type of stitch is that it facilitates the use of warp yarns. It is known that dimensional stability of the fabric can be improved by laying yarns against one side of the filling material and fastening them down with sewing thread. In the interlocking stitch, zigzagging of sewing thread between adjacent chains of loops provides a convenient means for holding the warp yarn in place. The warp yarn is simply laid against the fabric before the sewing thread is moved over it by the sewing thread guide.

The present invention is especially concerned with this warp yarn. It has been the custom to simply lay this yarn against the filling as it moves past the sewing needles. This results in a plurality of parallel warp yarns along the machine direction. As indicated, this increases dimensional stability in the machine direction.

A principal object of the present invention is to vary the pattern of the warp yarn by moving it across the filling as it is laid in place. Another object is to provide apparatus for accomplishing that purpose.

For the purposes of the present disclosure, the term warp will be applied to this yarn. While the various diagonal movements of the yarn across the fabric render it different from ordinary warp yarns, this term is convenient since it distinguishes from filling and sewing yarns also used in the fabric.

Various types of filling material can be formed into a fabric by sewing in accordance with the present invention. One preferred form of material is described in US. Pat. 2,890,579. A plurality of loose filling yarns are provided from continuous yarns which are wound back and forth across a kind of tenter frame by a carriage, and around heddle hooks on moving conveyor belts at either side of the frame. The conveyors are moving while the carriage traverses the space between them, so that the filling threads are more or less oblique to the machine direction and in two sets which are oblique to each other. That is after a set of parallel threads are caught on the hooks of one of the conveyors, the carriage moves directly across to the other conveyor. While the carriage moves across, the con veyors are moving perpendicularly to the carriage and, by the time the carriage reaches the other conveyor, that other conveyor has moved a short distance. Therefore the heddle hooks on which the threads are caught on the second conveyor are not directly opposite the hooks used on the first conveyor, and the threads are oblique to the machine direction. When the carriage returns to the first conveyor, an opposite effect is observed, and the threads laid down are oblique to the machine direction and to the threads laid down in the previous traverse. The filling threads mentioned above are cast off the heddle hooks after they are caught up by loops of sewing threads which gather them into clusters, separated by spaces where the sewing thread passes through the fabric.

Another type of loose filling material which can be used in this type of fabric is a batting or non-woven fiber web. This is a web of loosely arrayed fibers, extending more or less randomly in various directions. Webs of this type may be formed by depositing atmospherically' suspended fibers onto a moving screen, for example by suction applied through the screen. Webs also can be produced by carding a picker lap, and thickness can be increased by cross-laying a web in known manner. Strictly speaking, a batting or the like cannot be described as loose filling because the fibers are arranged more or less randomly in all directions. However, since a portion of the fibers will be more or less transverse or oblique to the loop chains, especially when derived from a crosslayered carded web, it can be considered to comprise loose filling for purposes of the present invention. Depending upon the relationship between the fibers, fabrics of this type may exhibit a tendency for the filling to be gathered into clusters by the sewing thread. i

It also is possible to apply the loop chain sewing to previously woven fabrics, plastic films and any other sheet-like material.

Substantially any textile fibers can be used for the warp, filling and/or sewing thread, and/or in a batting or other textile fill material. These include natural fibers such as cotton, wool, sisal, linen, jute and silk, manmade fibers and filaments such as regenerated cellulose rayon, polynosic rayon, cellulose esters, e.g. cellulose acetate, cellulose acetate/butyrate and cellulose triacetate and synthetic fibers and filaments such as acrylics, e.g. polyacrylonitrile, modacrylics such as acrylonitrile-vinyl chloride copolymers, polyamides, e.g. polyhexamethylene adipamide (nylon 66), polycaproarnide (nylon 6) and polyundecanoamide (nylon 11), polyolefin; e.g. polyethylene and polypropylene, polyester, e.g. polyethylene terephthalate, rubber and synthetic rubber, saran, glass, and the like. Sewing yarn sizes ordinarly are 15 to 1100 denier and filling yarns 15 to 3300 denier. Warp yarns may be, e.g. 15 to 5000 denier. Normally, stitches will be .4 to 4.5 mm. apart along the warp and about 1 to 7 mm. apart across the fabric. Typically, the sewn fabric weighs 1 to 24 ounces per square yard.

The invention will be better understood from the following detailed description of preferred embodiments, reference being made to the drawing, in which:

FIG. 1 is a plan view of the fabric;

FIG. 2 is a vertical section through a portion of the apparatus used to produce the fabric, showing the formation of stitches;

FIG. 3 is a view similar to FIG. 2, showing another step in the formation of stitches;

FIG. 4 is a perspective view of a portion of the apparatus;

FIG. 5 is a schematic view showing the paths of movement of sewing thread guides;

FIG. 6 is a plan view, partly schematic, of the apparatus;

FIG. 7 is a perspective view of the portion of the apparatus where stitches are formed;

FIG. 8 is a perspective view, similar to FIG. 7, showing another step in the operation;

FIG. 9 is a plan view, partly in section showing the drive mechanisms; and

FIG. 10 is a second along lines 1010 of FIG. 9.

As seen in FIG. 1, the sewing thread in the fabric is formed into interlocked chain stitching substantially along the warp or machine direction. Each sewing thread 1 is formed into a plurality of loops 2 spaced along the length of the fabric, each loop passing through the fabric. The loops are formed into parallel chains, but each chain is formed from two threads which alternately are formed into stitches of adjacent chains. For example, one chain of loops, designated 3 in the drawing, is formed from two threads 4 and 5. A first loop 6 is formed from thread 4, the next loop 7 is formed from thread 5 and the next loop 8 is formed again from thread 4, etc. Thread 4 also is formed into loops 9 in the chain 10 on one side of chain 3, alongside loop 7 and other loops in chain 3 which are formed from thread 5. Similarly, thread 5 also is formed into loops 11 in a chain 12 on the other side of chain 3, alongside loops 6 and 8 in chain 3. The arrangement is such that each sewing thread is interlocked with two others in adjacent stitch lines so that, if a thread breaks, it will not pull out a succession of stitches as it would if each chain were formed from a single thread.

The formation of this chain stitching is illustrated in FIGS. 2 and 3. A needle 13 is provided which has a point 14 at one end and a hook 15 adjacent the end. There is a groove 16 in the upper surface of the needle in which slides part of a bent wire latch 17. The needle is mounted for horizontal reciprocating motion.

A web 18 moves downwardly across the path of the 4 needle, and as the needle reciprocates it alternately pierces and is withdrawn from the web, the web being advanced downwardly while the needle is withdrawn.

A thread guide 19 is provided to insert the sewing thread 20 into the hook 15 when the needle extends through the filling material. As can be seen by comparing FIGS. 2 and 3, the thread guide moves up alongside the needle, across it and down on the opposite side, laying the thread in the hook 15 as it moves across. Then the needle is retracted and the latch 17 moves across the hook. At the same time, the web 18 moves down past the needle. As the needle moves forward to receive sewing thread again, the thread previously placed in the hook slides back onto the shank of the needle as seen at 21 to form a loop 22. When the needle retracts again and the latch 17 closes, the loop 22 slides forward toward the tip of the needle, pushed if necessary by the upright portion of latch 17. Since the hook 15 is closed by the latch, the loop 22 slides over the hook and is cast off the point 14 of the needle. At the same time, the thread in the hook is pulled through loop 22.

The thread guide 19 is mounted to alternately move up and across two needles, designated 23 and 24 in FIG. 5. Therefore, it describes a figure eight path 26.

For rapid machine operation, it is advisable to use circular eccentric cams for actuating the needles and the thread guides. As shown in FIG. 9, a needle bar 27 carrying the needles 13 is actuated by a connecting rod 28 extending from an eccentric rod 29 linked by a strap 30 of an eccentric cam 31 which is rotated by the motor-driven shaft 32 supported by a housing 33. Similarly, the reciprocating movement of the latches 17 required for closing the hooks of the needles is obtained by means of an eccentric cam 34 cooperating with a strap 35 actuating, through an eccentric rod 36, a connecting rod 37 that actuates the brackets to which the latches 17 are attached through a cam. The holders of the thread guides 19 are fastened to a guide bar 38 which, by means of suitably attached lever arms 39, is fixedly mounted on a shaft 40. This shaft, being rotatably mounted within bearings 41, is adapted to slide longitudinally back and forth and carries a short lever 42.

Lever 42 is connected with a coupling rod 43 linked to an eccentric rod 44. Rod 44 with its strap 45 encloses the eccentric cam 46 which, by means of an intermediate connecting rod 47, moves the thread guides up and down. Aside from this reciprocating movement, the thread guides must undergo an axially transverse back and forth movement in order to insert threads into the hooks of the needles and to alternate between needles. For this purpose, the thread guides 19 and the shaft 40 carrying the same are operated to perform one complete back and forth movement while the needles are moved twice in and out. To accomplish this, a pinion 48 keyed to the shaft 32 engages a spur wheel 49 of twice its size. Consequently, the spur wheel rotates at half of the speed of the shaft 32.

Spur wheel 49 is fixedly connected with an eccentric cam 50 Whose strap member 51 is linked by an eccentric rod 52 to a connecting rod 53 axially slidable in a bearing 54. When in operation, the rod 53 and its linkage 55 impart axial reciprocation to the shaft 40 by actuating an angle lever 56 rotatably mounted to a pivot 57. The tension spring 58 fastened about the shaft 40, between one of the bearings 41 and the adjacent lever arm 39 of the guide bar 38 aids the axially oscillating movement by forcing the shaft against an adjusting screw 59 connecting the free end of angle lever 56 to that of the shaft 40.

A filling yarn supply for use when loose yarn is employed as the filling, is illustrated in FIG. 6. For simplicity, a single yarn is shown, indicated by the numeral 60. At opposite sides of the apparatus, there are chains 61 and 62, each trained around sprocket wheels and driven by a motor, not shown. On each of the chains 61 and 62 there are a plurality of upright heddle hooks 63 around traversed back and forth above the chains 61 and 62. The arrangement is such that as the carriage moves a bit past the hooks on one side of the chains, the chain moves and the yarn is turned around one or more hooks. Then the carriage moves in the opposite direction across to the other chain and past that chain so that the procedure is repeated.

In actual practice, the carriage 64 carries several yarn guides and a plurality of yarn ends is laid down as superimposed layers, each layer being at an angle to the layer next to it. The filling yarn remains in this position until loops are formed by the sewing operation, and the filling is cast off the chains 61 and 62. Then the filling takes the form of generally parallel clusters of yarn separated by spaces at sewing thread stitch insertion points.

In lieu of this type of filling yarns, various types of sheet-like materials may be used, as described above. They may be supplied from a beam and carried to the sewing needles by the chains 61 and 62.

The warp yarns are conveniently applied against the filling as the latter moves down to the line of sewing needles. They are then caught by the sewing thread and tied down against the filling. They are supplied conveniently from a package above the sewing needles and move downwardly through a yarn guide. In accordance with a preferred embodiment of the present invention, there is a yarn guide mounted just above the needles and means are provided for oscillating the yarn guide transverse to the filling, i.e. parallel to the line of needles.

A suitable means for supplying warp yarn is shown in FIG. 4. A bar 65 is mounted above the row of needles 13 with a plurality of pins 66 extending from the bar parallel to the needles. The spaces between pins 66 may be about the same as spaces between adjacent needles 13, or larger.

As seen in FIG. 6, oscillation of the bar 65 is achieved by turning a grooved cam 67, the bar 65 carrying a cam follower 68 which moves in the groove of cam 67. More elaborate patterns may be produced, e.g., by attaching the end of bar 65 to a servo motor whose rotation is controlled by punch cards or a computer. Movement can be obtained by fitting a rack 69 to one end of the bar 65 and rotating a cooperating pinion 70 with the servo motor 71, as seen in FIG. 4.

It will be appreciated that various patterns of diagonal yarns may be attached to the reverse side of the fabric. If desired, two or more bars 65 may be used, supplying different colored yarns, yarns of different sizes, etc. All such patterns tend to increase the diagonal dimensional 6 stability of the fabric and can provide ornamental ef fects as well.

It will be obvious that the embodiments described are for purposes of illustration only and that various changes may be made in the apparatus and method without departing from the scope of the invention, as defined in the appended claims.

I claim: 1. In a knit fabric comprising a plurality of substantially parallel chains of loops formed from a sewing thread and a filling material, said chains of loops extending along one side of said filling material with threads connecting between loops extending through said loops and said filling material and along the other side of said filling material, and

a warp yarn laid against and conforming to the surface of said other side, substantially the whole length of the warp yarn being held against said filling material by said sewing threads connecting between loops,

the improvement in which at least a portion of the length of said warp yarn extends at an angle with respect to said chains and across at least two of said chains, to increase the dimensional stability of said fabric along a bias and to provide an ornamental pattern.

2. A fabric as set forth in claim 1 in which said filling comprises loose filling yarns gathered into substantially parallel clusters generally perpendicular to said chains and separated by spaces where said sewing thread passes through said filling.

3. A fabric as set forth in claim 1 in which said filling comprises a carded nonwoven fiber web.

References Cited UNITED STATES PATENTS 2,890,579 6/1959 Mauersberger 66192 2,743,596 5/1956 Noe 66-84 3,030,786 4/1962 Mauersberger 66-84 3,134,248 5/1964 Kubelka et a1. 6685 XR 3,364,701 1/1968 Carman 6684 3,392,078 7/1968 Duhl 66192 XR FOREIGN PATENTS 1,095,507 12/1954 France. 1,467,783 1/1967 France.

35,364 11/1965 Germany.

RONALD FELDBAUM, Primary Examiner 

